The present invention relates to a roll control system for an automotive vehicle, and more specifically relates to a vehicle roll control system of the vehicle height adjustment type.
The present invention has been described in Japanese Patent Application Ser. No. Sho 61-039551 (1985), filed by an applicant the same as the entity assigned or owed duty of assignment of the present patent application; and the present patent application hereby incorporates into itself by reference the text of said Japanese Patent Application and the claims and the drawings thereof; a copy is appended to the present application.
Further, the present inventors wish hereby to attact the attention of the examining authorities to copending Patent Applications Ser. Nos. 06/921,138; 06/921,251; 06/921,450; 06/921,451; 06/921,468; 07/016,944; and 07/026,468, which may be considered to be material to the examination of the present patent application.
In general, in the operational conditions where a vehicle such as an automobile turns at a speed not less than a particular determinate turning speed value, the body of the vehicle experiences rolling, i.e. the vehicle body inclines in the radially outward direction, and this rolling results in deterioration of the drivability of the vehicle.
In order to cope with the above problem--as described in the specifications of, for example, Japanese Patent Applications Ser. Nos. Sho 60-235659, Sho 60-235660, and Sho 60-235661, which are applications filed by an applicant the same as the entity assigned or owed duty of assignment of the present patent application, and the subject matters of some or all of which are included in the above identified Patent Applications which are copending with the present Patent Application as described above, but which it is not hereby intended to admit in any way as prior art to the present application except to the extent in any case mandated by applicable law--there have been proposed to fit to a vehicle various types of vehicle height adjustment systems comprising: a plurality of actuators which are provided for resiliently suspending the vehicle wheels from its body and are adapted to increase or decrease vehicle height at locations corresponding to the associated vehicle wheels as respective results of supplying or discharging working fluid to or from variable volume working fluid chambers of said actuators; a plurality of working fluid supplying and discharging means which are provided corresponding to the actuators and which serve to supply or discharge the working fluid to or from said actuators; a vehicle speed detecting means for detecting the road speed of the vehicle; a steering angle detecting means for detecting the steering angle of the vehicle; and a control means for controlling the working fluid supplying and discharging means predictingly computing the roll angle of the vehicle body based upon the vehicle speed and the steering angle as sensed by these detecting means therefor, and for in accordance with this predicted roll angle reducing the rolling of the vehicle body so as to keep said vehicle body roll within a predetermined range.
In a vehicle equipped with such a vehicle height adjustment system as described above, however, when it should happen that, while the vehicle is turning in a certain direction, the steering wheel of the vehicle is temporarily turned in the direction opposite to said turning direction--as for example is done when drifting or skidding of the vehicle occurs while said vehicle is being driven around a curve at relatively high speed--then, since the working fluid supplying and discharging means are controlled so as to increase the vehicle height on the radially inner side of the curve based upon the steering angle as sensed by the steering angle detecting means, and since this sensed steering angle is now opposite to the actual direction of turning of the vehicle, the rolling of the vehicle body is temporarily increased even over the rolling amount which would be present if no roll control system were provided to the vehicle, and this effect, rather than improving drivability and controllability of the vehicle, on the contrary actually deteriorates these operational characteristics thereof. Further, the comfortability of the vehicle is deteriorated, and the cornering characteristics thereof also suffer.